November Weather Discussion. Rollercoaster Pattern.

[srainhoutx]

HPC:

USED PRIMARILY THE 00Z ECMWF TO UPDATE THE PRELIMINARY FRONTS AND
PRESSURES FOR DAYS 3 THROUGH 6...WITH A SHIFT TOWARDS THE 00Z
ECENS MEAN DAY 7 TO ADDRESS THE UNCERTAINTIES IN SYNOPTIC DETAIL
INHERENT AT THAT TIME RANGE. THE MODELS ARE IN ABOVE AVERAGE
AGREEMENT FOR THIS FORECAST PERIOD...WITH A WEDGE OF MODIFIED
ARCTIC AIR OVER WESTERN CANADA CUTTING DOWN ON THE DOMAIN IN WHICH
THE OPEN FLOW ACROSS THE CONTINENT COULD BE HANDLED DISPARATELY BY
THE GUIDANCE. THE EUROPEAN GUIDANCE WAS USED OVER THE OTHER
MODELS FOR SURFACE PRESSURES...SINCE BY AND LARGE...IT CONTINUES
TO MAINTAIN A VERIFICATION EDGE DURING THE MEDIUM RANGE. THE
TIMING OF THE WAVE RIPPLING ALONG THE POLAR FRONT OVER THE CENTRAL
STATES TOWARD THE END OF THE PERIOD IS PROBABLY THE BIGGEST
QUESTION MARK...WITH THE ECMWF AND GEM GLOBAL ON THE FAST SIDE OF
THE GUIDANCE.

[snowman65]

In English?

[srainhoutx]

Basically, the cold air is coming. Will it be modified? Certainly. There are issues in guidance regarding the storm system rotating around the Polar Vortex into the Plains and the timing or rippling that the HPC is referring to is the big question mark via overnight guidance. Stay Tuned. One thing that also is of note is the storminess that will lead to building some snow pack to our N. That will play a big role on any future Arctic intrusions and airmass modification that may well occur in the active pattern ahead.

[srainhoutx]

The 12Z GFS suggests the Arctic Front may be a bit slower arriving, but a very chilly 1040mb+ dome of Arctic High Pressure is depicted dropping S into the Plains. With that said, I believe the models will struggle with the shallow nature of the Arctic Air and the front may infact arrive sooner that it's showing at this range...

[snowman65]

Thanks Srain. I'm still trying to monitor Central/Eatern Tennessee for Thanksgiving week.

[biggerbyte]

Hi, Snowman.

I have a sister that lives in eastern TN., right on top of one of the mountains. Her children live down in the valley.

[snowman65]

Sweet.....We will be with in laws in Gainesboro and will be going to G-burg and V-forge on Tues and Wed. Can't wait...

[TexasMetBlake]

The extended is fun but truly unbelievable. It shows a 1040 high crossing the Red River into Texas at 336 hrs (12z gfs). Yeah, and John Madden is a finicky eater. I can tell you though that I do like the trends. With the anomalies going negative over Greenland and the ridge pumping up over the west coast, it won't be long before something dislodges out of Alberta. I just wish the source region was colder---though I'm not sure how the curret temps (single digits in the Yukon) relate to the average departure.

[srainhoutx]

The extended is fun but truly unbelievable. It shows a 1040 high crossing the Red River into Texas at 336 hrs (12z gfs). Yeah, and John Madden is a finicky eater. I can tell you though that I do like the trends. With the anomalies going negative over Greenland and the ridge pumping up over the west coast, it won't be long before something dislodges out of Alberta. I just wish the source region was colder---though I'm not sure how the curret temps (single digits in the Yukon) relate to the average departure.

The 12Z Euro looked rather interesting as well. When we see a Pacific Ridge and waves suggested by models rotating under the Polar Vortex that is modeled to drop S into Southern Canada/Upper Great Lakes Region, it's time to pay attention.

Some TX/OK AFD snips this afternoon...

Midland/Odessa...

OF INTEREST WILL BE AN ARCTIC AIRMASS THAT
STARTS TO SLIDE SE IN LEE OF NRN ROCKY MTNS LATE SUNDAY. WOULDN/T
BE SURPRISED TO SEE A WARM/DRY WINDY DAY SUNDAY AS MID LEVEL WINDS
INCREASE FURTHER IN ADVANCE OF UPPER LOW MOVING INTO THE NWRN
STATES. AS TYPICAL MODELS HOLD ARCTIC N BUT THERE ARE INDICATIONS
OF A KICKER NRN STREAM SHRTWV THAT MAY FURTHER INCREASE THE CHANCE
FOR ARCTIC AIR TO SURGE S TUE/WED?

[Andrew]

The extended is fun but truly unbelievable. It shows a 1040 high crossing the Red River into Texas at 336 hrs (12z gfs). Yeah, and John Madden is a finicky eater. I can tell you though that I do like the trends. With the anomalies going negative over Greenland and the ridge pumping up over the west coast, it won't be long before something dislodges out of Alberta. I just wish the source region was colder---though I'm not sure how the curret temps (single digits in the Yukon) relate to the average departure.

This is about as cold as you can get for November:





While that is off in fantasy land I do agree that things are looking positive for a cold blast sometime in the near future. Think if a blast like this happened in January...

[TexasMetBlake]

Andrew--that is just a forecast. I was talking about the current temps in Siberia, Alaska and the Yukon. I can certainly tell that far northern territories of Canada, for the first time, are really beginning to cool down (which would verify the forecast being shown above). Take a look at the temps below.

Alaska:


Canada: (notice the pinks)



Siberia: (not as cold as I had thought it would be)

[srainhoutx]

This cold is centered over the Arctic. What's interesting is the continued building of that cold air as time goes on. Also, notice the sea ice charts...

[Andrew]

Andrew--that is just a forecast. I was talking about the current temps in Siberia, Alaska and the Yukon. I can certainly tell that far northern territories of Canada, for the first time, are really beginning to cool down (which would verify the forecast being shown above). Take a look at the temps below.

Alaska:
http://data.hamweather.net/contours/wx4 ... points.png

Canada: (notice the pinks)

http://www.findlocalweather.com/weather ... ure_i1.png

Siberia: (not as cold as I had thought it would be)

http://www.findlocalweather.com/weather ... ure_i1.png

No I know. I agree that this cold air will come down and is building I am just saying that this is 384h out so it will be interesting to see if that verifies. I know you were talking about the cold air trapped up north, I was just saying that it would be pretty incredible if the GFS verifies.

[Mr. T]

I think it is a bit irrelevant pointing out what current temps look like right now as the really cold stuff doesn't start flowing into Canada until this weekend. I know this would mean more if it were January, but you can still plunge into the 20s this time of year, and that is record territory for our area. Certainly the type of airmass that will be plunging southward would be capable of doing that, but of course the question remains whether or not the arctic air ever makes it here.

[Mr. T]

Basically, the cold air is coming.

I definitely agree with this. The upper air pattern being depicted by all global models supports an unusually strong arctic airmass for this time of year to begin oozing into the Northern Plains this weekend. Thereafter lies questions we cannot answer at this point. Will the arctic air be able to take a trip south down the Rockies into Texas? Or will we only get a piece of it?

I like the odds of a fairly strong front around Turkey Day, as HGX suggests. We may only cool into the 30s again, but I'd suspect the cold air (whatever is left of it) would make it here eventually. I will say that we will likely see some very warm days before then.

[srainhoutx]

Basically, the cold air is coming.

I definitely agree with this. The upper air pattern being depicted by all global models supports an unusually strong arctic airmass for this time of year to begin oozing into the Northern Plains this weekend. Thereafter lies questions we cannot answer at this point. Will the arctic air be able to take a trip south down the Rockies into Texas? Or will we only get a piece of it?

I like the odds of a fairly strong front around Turkey Day, as HGX suggests. We may only cool into the 30s again, but I'd suspect the cold air (whatever is left of it) would make it here eventually. I will say that we will likely see some very warm days before then.

Those are the days that raises an eyebrow...

[srainhoutx]

Good morning. Should be a breezy/chilly day in full sunshine. Enjoy! The Arctic Intrusion is still looking likely next week and just perhaps a reinforcing shot of even colder air to follow. Some timing differences between the GFS and Euro, but it does appear that a cross polar flow may well shape up bring some mighty chilly air S. We will need to watch for any frozen precip in the Plains that may aid in less air mass modification in the longer range. It's hard to believe almost a year ago we were mentioning some of the same things. Interesting.

Euro Day 10 500mb Anomalies



GFS 2 Meter Temps @ 372 Hours

[wxman57]

Here's an extended range GFS meteogram for IAH. Note that it's the predicted 2 meter temps for 6am and 6pm each day - NOT the lows/highs for each day. However, the 6am temp will be close to the low of the day. The 6pm temp will occur 4 hours after the daily high, so you have to add another 5-7 degrees (sunny day) to get close to the high temp.

[srainhoutx]

To add to wxman57's meteogram is the 11-15 day GFS Precip charts. Notice what appears to be a Coastal Low developing in S TX tracking E over time...just looking at trends in the long range...

[srainhoutx]

Also of note is the AO daily charts. Notice the sharp drop projected. Fits nicely with what we are seeing in the Operational Models...